Apparatus for controlling initial engagement of cutters with concrete pavement surfaces

ABSTRACT

A tractor or wheel loader carries a grooving unit, including a gang of rotating saw blades, for cutting parallel grooves in a concrete pavement. A shock absorber device prevents the saw blades from being lowered rapidly to impact against the pavement and thereby possibly damage the blades. The shock absorber device is initially lower than the blades and contacts the pavement first, gradually retracting to permit gradual lowering and engagement of the saw blades with the pavement.

United States Patent Inventor Joseph B. Fowkes Salt Lake City, UtahAppl. No. 872,494

Filed Oct. 30, 1969 Patented Sept. 28, 1971 Assignee Christensen DiamondProducts Company Salt Lake City, Utah APPARATUS FOR CONTROLLING INITIALENGAGEMENT OF CUTTERS WITH CONCRETE PAVEMENT SURFACES 24 Claims, 5Drawing Figs.

US. Cl 299/39, 5 1/170 Int. Cl 1601c 23/09 Field of Search 299/39, 40 4l; 5 1/176 [56] References Cited UNITED STATES PATENTS 982,759 1/1911Bagalio 51/176X 3,266,846 8/1966 Luk'sch et a1. 299/39 3,414,327 12/1968Austin 299/39 X Primary Examiner- Ernest R. Purser Attorney-BernardKriegel ABSTRACT: A tractor or wheel loader carries a grooving unit,including a gang of rotating saw blades, for cutting parallel grooves ina concrete pavement. A shock absorber device prevents the saw bladesfrom being lowered rapidly to impact against the pavement and therebypossibly damage the blades. The shock absorber device is initially lowerthan the blades and contacts the pavement first, gradually retracting topermit gradual lowering and engagement of the saw blades with thepavement.

APPARATUS FOR CONTROLLING INITIAL ENGAGEMENT OF CU'I'IERS WITH CONCRETEPAVEMENT SURFACES The present invention relates to apparatus for cuttinggrooves in concrete and similar roadway surfaces, such as in highway andairport runways surfaces.

Apparatus has been provided for cutting grooves in concrete roadwaysurfaces. One such apparatus includes a gang of closely spaced rotatingsaw blades or discs that are moved along the roadway to cut shallowparallel grooves therein, to improve traction of vehicle and aircraftwheels thereagainst particularly during inclement weather. Theparticular four-wheel vehicle with a grooving cutter mechanism mountedthereon forms the subject matter of the application of Frank L.Christensen and Takeshi Mori, Ser. No. 851,193 filed Aug. 19, 1969 forMachines for Cutting Grooves in Concrete and Similar Roadway Surfaces.In such machine, the gang of saw blades is shiftable from a positionelevated above the roadway surface into engagement therewith. It is,however, important to prevent the saw blades from being droppedaccidentally or moving rapidly upon the pavement surface, since theimpact could damage the saw blades. A gang of saw blades, with a matrixat their peripheral cutting portions containing diamonds, is expensive,a gang capable of grooving an overall pavement width of above feetcosting in the neighborhood of $10,000.00

The present invention prevents accidental or too rapid lowering of thecutters of the grooving unit onto the pavement, controlling the verticaldown feet of the cutters into the cutting position in the pavement orroadway. A shock absorber means is provided which first contacts theroadway and prevents engagement of the saw blades, or other cutters,therewith, retaining them a short distance above the roadway. After theshock absorber unit engages the roadway, it effects gradual lowering ofthe cutters into the cutting position, the shock absorber unit thenbeing ineffective. Upon elevating of the cutter members from theroadway, the shock absorber unit automatically repositions itself toextend before the lowermost portion of the cutters, so that subsequentlowering of the grooving unit toward the pavement will again firstcontact the shock absorber unit therewith, followed by gradual loweringof the cutters the short distance necessary to bring them intoappropriate cutting position with respect to the pavement.

More specifically, the shock absorber mechanism is operativelyassociated with the mechanism for raising and lowering the cutters intoand from engagement with the pavement, such that elevating of thecutters from the pavement automatically extends the shock absorbermechanism so that it engages the pavement surface and prevents thecutters from bearing there against, after which the shock absorber, asnoted above, automatically retracts to permit the gradual lowering ofthe cutters into their cutting position with respect to the pavement. Ifthe lowering mechanism were to suddenly drop the grooving unit towardthe pavement surface, the cutter blades could not contact the lattersince the shock absorbers would first engage the surface, preventing theblades from contacting the latter. The cutting action then occurswithout interference from the shock absorber mechanism. When the cuttersare elevated from the pavement, the shock absorber is againautomatically brought into its operative position in response toelevation of the cutter or grooving unit from the pavement.

This invention possesses many other advantages, and has other purposeswhich may be made more clearly apparent from a consideration of a formin which it may be embodied. This form is shown in the drawingsaccompanying and forming part of the present specification. It will nowbe described in detail, for the purpose of illustrating the generalprinciples of the invention; but it is to be understood that suchdetailed description is not to be taken in a limiting sense.

Referring to the drawings: FIG. 1 is a partially diagrammatic sideelevational view of a machine embodying the invention, with its groovingunit elevated from a roadway surface and its shock absorber unit inextended position;

FIG. 2 is an enlarged side elevational view of a portion of the groovingunit, located in engagement with the roadway surface, with the shockabsorber unit retracted, and a vehicle wheel raised from the roadwaysurface;

FIG. 3 is an enlarged cross section, taken along the line 3- 3 on FIG.2;

FIG. 4 is an enlarged cross section, taken along the line 4- 4 on FIG.2; and

FIG. 5 is a diagrammatic view-of the hydraulic system of the machine.

With the exception of the shock absorber mechanism and the hydraulicsystem illustrated in the drawings, the machine for cutting grooves S inconcrete and similar roadway surfaces R is illustrated in theabove-identified US. patent application. In view of such illustrationand description only those portions of the apparatus will be describedfor the purpose of setting forth the present invention, since a completedescription is unnecessary to its understanding. The machine includes afour wheel vehicle 10 which may be of a conventional tractor or wheelloader type manufactured by the Caterpillar Tractor Company. It has amain frame or chassis 11 with one set or a pair of steerable wheels 12including pneumatic tires 13, which for steerable wheels 12 includingpneumatic tires 13, which, for convenience, may be referred to assteerable front wheels, and another set or pair of wheels 14 includingpneumatic rubber tires which, set or pair of wheels 14 for convenience,may be referred to as r ear wheels. The unit has the usual internalcombustion engine 15, such as a diesel engine, that drives through atorque converter or other variable ratio transmission (not shown) toboth the front and rear wheels to effect a four-wheel drive. Thesteerable wheels I2 are steered through a known mechanism by appropriateturning of a stee ring wheel 16 manipulated by the driver. A pair ofspaced swing ro lift arms 17 are pivotally connected at their forwardend portions to the upper part of the frame or chassis by hinge pins 18,the rear or lower ends of these arms being connected by pins 19 to themovable frame 20 of the grooving unit G of the machine. A pair oflaterally spaced upper arms 21 are also connected by forward connectorpins 22 to the swing arms I7 and by rear connector pins 23 to themovable frame 20 of the highway grooving unit.

The movable frame 20, which is disposed behind the rear wheels 14 of themachine, carries an internal combustion engine 24, such as a dieselengine, the crankshaft 25 of which rotates a shaft structure 26 througha suitable transmission, such as a belt and pulley transmission 27, 28,29, 30, rotatably supported in bearings fixed to the fame. The driveshaft structure 26 is suitably fixed to a saw blade assembly 31,comprising a plurality of saw discs or cutters 32 separated by spacers33 and clamped to a mandrel 34 suitably attached to the drive shaftstructure. The rim portion of each saw blade 32 may comprise a matrix ofdiamonds and other material for effectively cutting the concrete roadwaysurface. The saw blade or cutter assembly 31 may assume any requiredform, one such assembly being illustrated and described in the patentapplication of Warren 1. Hughes and Donald H. Mabcy, Scr. No. 788,838,,filed Jan. 3, I969, for Rotary Cutter Assembly.

As illustrated, the depths of penetration of the saw blades into theroadway surface, that is to say, the depth of cut of the parallel sawblades in producing the grooves S in the roadway surface, is determinedby a pair of depth-of-cut rollers 35 located at opposite sides of themovable frame. Thus, a support arm 36 is pivotally mounted on the frameat each of its sides by a pivot pin 37, each arm having an axle 38rotatably mounting a depth-of-cut roller 35 engageable with the roadwayor airport runway surface R. The end of the support arm 36 opposite thepivot pin 37 is connected by means of a pin 39 to a generally verticallyadjustable rod or shaft 40 having an upper threaded portion passingthrough a boss 41 fixed to the movable frame 20. Threadedly mounted onthe threaded shaft portion and above and below the boss are nuts 42bearing against washers 43 engaging the upper and lower surfaces of theboss. Appropriate turning of the nuts at each side of the frame willeffect vertical adjustment of the shaft 40 to move the forward ends ofthe support arms up or down and shift the axes of the depth-of-cutrollers 35 with respect to the axis of the cutter shaft 26. The rollers35 are located a desired distance above the lower periphery of the sawblades 32, thereby determining the depth of penetration of the sawbladed or cutters into the roadway surface R, which determines the depthof the grooves S cut into such surface. Following adjustment of thedepth-of-cut rollers, the nut 42 are retightened against the washers 43and the washers against the upper and lower sides of the bosses 41 toretain the depth-ofcut rollers in the position to which they have beenadjusted.

The movable frame and saw blade assembly 31 and depth-of-cut rollers 35carried thereby are shiftable as a unit in a vertical direction to bringthe saw discs and rollers into and out of engagement with the pavementsurface. The shifting or actuating mechanism includes a pair oflaterally spaced cylinders 45 having lower ends connected hinge pins 46to the frame or chasses 11 of the wheel loader vehicle. Each cylinderhas a piston 47 slidable therein and secured to a piston rod 48extending from the upper end of the cylinder and connected by a pin 49to a swingable arm 17. The introduction of fluid under pressure into thehead or lower ends 50 of the cylinders will shift the pistons 47 andpiston rods 48 upwardly to swing the arms 17 and the entire movableframe 20 upwardly with respect to the roadway or pavement surface. Onthe other hand, the bleeding of fluid under pressure from the head endsof the cylinders and the introduction of such fluid under pressure intothe upper or rod ends 51 of the cylinders will effect retraction of thepiston rods 48 into the cylinders and downward movement of the swingarms 17 and the movable frame 20 to bring the depth-of-cut rollers 35and the saw blades 32 downwardly. Prior to lowering of the grooving unitG, rotation of the saw blade assembly 31 by the internal combustionengine 24 on the frame is initiated, operating through the transmission2730. The continued application of fluid under pressure into the rodends 51 of the cylinders, after the shock absorber portion A of thegrooving unit, described hereinbelow, has contacted the pavement, willeffect elevation of the rear of the frame or chassis 11 and of the rearwheels 14 from the pavement surface. Thereafter, as set forthhereinbelow, the shock absorber unit A gradually retracts to slowlylower the rotating saw blades 32 and depth-of-cut 35 into contact withthe pavement surface R. The weight of the wheel loader type of mechanism10, to which the movable frame 20, saw blade assembly 31, anddepth-of-cut roller mechanism has been secured, is quite large, and morethan adequate for insuring penetration of the cutters 32 into theroadway surface to the desired depth, with the depth-of-cut rollers 35engaging the roadway surface to limit the extent of penetration of thesaw blades into the pavement.

Two shock absorber devices A are used being laterally spaced from oneanother. Each unit is carried by the movable frame 20. As shown, eachunit includes a cylinder 60 mounted on the movable frame by a pin 61passing through the upper end 62 of the cylinder and pivotally securingit to the frame 20 (FIG. 4). The cylinder has a piston 63 slidabletherein secured to a piston rod 64 extending from the rod end 65 of thecylinder and connected by a pivot pin 66 to a support 67 pivoted uponthe movable frame 20 by a hinge pin 68. The support carries an axle 69rotatably mounting a pavement engaging wheel 70. When fluid underpressure is introduced into the upper or head ends 62 of the cylinders,the pistons 63 therein are moved downwardly to move the piston rods 64downwardly and swing the supports 67 about their hinge pins 68 andthereby lower the wheels or rollers 70. When in their lower position,such rollers 70 will contact the pavement R, when the movable frame 20is shifted downwardly, before the saw blades 32 can contact thepavement, the latter being prevented from engaging the pavement. Whenfluid under pressure is introduced into the rod ends 65 of the cylinders60, the pistons 63 are elevated therein, which swing the supports 67upwardly-and bring the rollers 70 upwardly to permit engagement of thesaw blades 32 and depth-of-cut rollers 35 with the pavement. Asdescribed hereinbelow, such elevation or retraction of the supports 67,rollers 70, piston rods 64 and pistons 63 occurs gradually so that therotating saw blades 32 are brought in a gradual manner into contact withthe pavement R and into grooving relation to the pavement.

As illustrated, the vehicle or wheel loader 10 has a pump 71 drivenconstantly by the vehicle engine 15 when it is rotating, which draws afluid or liquid, such as oil, from a supply tank 72 through a suctionline 73a and delivers such fluid under high pressure to a discharge line73 running to a three-position valve 74 mounted on the vehicle. A returnline 75 extends from this valve to the supply tank 72 to returnhydraulic fluid thereto. The three-position valve 74 is actuated by theoperator through a control lever 76 and suitable linkage 77 running tothe movable spool 78 of the three-position valve. A fluid pressure line79 extends from one end of the three-position valve to a junction 80,another line 81 extending from this junction to the lower or head end 50of each hydraulic lift cylinder 45. Another line 82 extends from thisjunction to the head end 62 of each of the shock absorber cylinders 60,each of these latter lines having a flow control valve 83 thereinincluding a metering orifice 84 and a check valve 85 having a seat 87and a ball 86 engageable therewith to permit free flow of fluid throughthe line 82 toward the cylinder 60, but which seats to preclude flow offluid from the cylinder back towards the junction 80. Another line 88extends from the three-position valve 74 to another junction 89. a fluidline 90 running from thisjunction to the rod end 51 of each cylinder 45.and a fluid line 91 from the junction 89 to the rod end 65 of each ofthe shock absorbing cylinders 60.

The hydraulic system is illustrated diagrammatically in FIG. 5, Asdisclosed therein, the three-position valve 74 can occupy a neutralposition, in which fluid under pressure from the pump 71 flows throughthe pump discharge line 73 into the valve and then returns therefromthrough the return line 75 to the supply tank 72. When in this position,fluid cannot flow through either of the other lines 79, 88 to either thehead or rod ends of the lift cylinders 45 or to either the head or rodends of the shock absorber cylinders 60. Actuation of the control liver76 by the operator in on e direction, as upwardly as disclosed in FIG.5, will place the high pressure pump discharge line 73 in communicationwith the fluid lines 79, 80, 81, 82 running to the head ends 50 of thelift cylinders 45 and to the head ends 62 of the shock absorbercylinders 50, elevating the pistons 47 in the lift cylinders to elevatethe entire grooving mechanism G from the pavement R, and at the sametime shifting the pistons 63 in the shock absorber cylinders downwardlyto lower the shock absorber wheels or rollers 70. Fluid in the rod ends51 of the lift cylinders 45 and in the rod ends 65 of the shock absorbercylinders 60 can then return through the return line 90, 91, 89. 88, 75,to the supply tank 72.

To effect engagement of the shock absorber A and saw blades 32 with thepavement, the control lever 76 is moved in the opposite direction, tolower the spool 78 of the three-position valve to it slower position asseen in FIG. 5, which will place place the high pressure pump dischargeline 73 in communication with the fluid lines 88, 89, 90, 91 running tothe rod ends 51 of the lift cylinders 45 and to the rod ends 65 of theshock absorber cylinders 60. At the same time, the head ends 50 of thelift cylinders 45 and the head ends 62 of the shock absorber cylinders60 are placed in communication with the return line 75 running to thesupply tank 72. The pistons 47 in the lift cylinders are then loweredtherewithin to shift the movable frame 20 downwardly, together with theshock absorber mechanism A, depth-of-cut rollers 35 and saw blades 32carried thereby, the fluid pressure in the rod ends 65 of the shockabsorber cylinders 60 tending to elevate the pistons 63 therein.However, the fluid in the head ends 62 of these cylinders can only flowoutwardly therefrom at a relatively slow rate, since all of such fluidmust pass through the choke orifices or metering devices 84 beforeflowing through the lines 82, 80, 79, 75, back to the supply tank 72.

Fluid under pressure is permitted to flow into the rod ends 51 of thelift cylinders 45 until the shock absorber rollers 70 engage thepavement R, the lift cylinders then moving upwardly to raise the rearend of the chassis 11 and the rear wheels 14 from the pavement surface,so that a large portion of the weight of the vehicle and of the groovingunit G is then being borne by the wheels or rollers 70 of the shockabsorber unit, When the rear wheels 14 are elevated from the pavement,which for example, may be a distance of about 2 inches thereabove, thecontrol lever 76 may be manipulated to place the three-position valve 74in the neutral position, thereby trapping fluid in the rod ends 51 ofthe lift cylinders and in the rods ends 65 of the shock absorbercylinders. How ever the weight of the rear portion of the vehicle isbeing imposed on the hydraulic fluid in the rod portions of the liftcylinders 45, which thereby maintains a high unit pressure of fluid insuch cylinders 45, which thereby maintains a high unit pressure of fluidin such cylinders, this pressure being transmitted through the fluidlines 90, 91 running to the rod ends of the shock absorber cylinders 60.Thus, there is fluid pressure in the shock absorber cylinders elevatingthe pistons 63 therein, the rate of elevation being determined by therate at which the liquid in the head ends 62 of these cylinders can flowthrough the choke orifices 84 into the lines 82, 81 running to the headends 50 of the lift cylinders 45. As fluid is forced out of the headends 62 of the shock absorber cylinders, the rollers 70 and the supports67 carrying them move upwardly about their pivot pins 68 to permitdescent of the movable frame and engagement of the rotative saw blades32 against the pavement, the saw blades rotating to cut grooves Stherein to a depth determined by contact of the depth-ofcut rollers 35with the pavement surface.

When the grooving unit is to be raised by the operator, the valve 74 isshifted to the upper position (Fig. 5), so that fluid under pressureflows into the head ends 50 of the lift cylinders 45 and also the headends 62 of the shock absorber cylinders 60. The lift pistons 47 arethereby elevated to swing the arms 17 upwardly and lift the entiregrooving unit G from the pavement, beginning the cutters 32 anddepth-of-eut rollers 35 out of engagement therewith, as well as raisingthe shock absorber wheels 70, the fluid under pressure also beingimposed through the lines 82 and past the check valve 85 into the headends 62 of the shock absorber cylinders 60, to shift the pistons 63 androds 64 downwardly and relocate the rollers 70 in their .lower positionwith respect to the movable frame 20. The

pistons and piston rods in the shock absorber cylinders are extendedquite rapidly, since fluid under pressure can flow relatively freelypast the check valves 85 and into the head ends of the cylinders, asdistinguished from the relatively slow rate of flow of the fluid fromthe head ends 62 of the cylinders 60 through the choke orifices 84 whenthe pistons 63, rods 64 and the rollers 70 are to be elevated. Duringelevation of the lift pistons 47 and lowering of the shock absorberpistons 63, the oil from the rod sides of their companion cylindersflows through the lines 90, 91, 88 and through the control valve 74 intothe return line 75 that carries it back to the supply tank 72.

Following full elevation of the cutters of the grooving unit G, whichwill be first accompanied by reengagement of the rear wheels 14 with thepavement R, the valve 74 can be shifted to its neutral position, therebytrapping oil in the head ends 50 of the lift cylinders 45 and in thehead ends 62 of the shock absorber cylinders 60, which will retain thegrooving unit G in the elevated ed position, as well as the shockabsorber rollers 70 in their maximum depending position with respect tothe saw blades 32 and the depth-of-cut rollers 35. The weight of thegrooving unit G and the swing arms 17 is large and is being imposedthrough the piston rods 48 and the pistons 47 on the liquid in the headends 50 of the lift cylinders, such liquid under pressure also behindimposed through the fluid in the lines 81, 82 on the liquid in the headends 62 of the shock absorber cylinders 60, thereby insuring a largepressure holding the shock absorber rollers 70 in their lowermostposition and capable of resisting upward movement relative to themovable frame 20 of the grooving unit G.

When the control valve 74 is manipulated to lower the grooving unit Ginto its working position, oil can flow from the head ends of the liftand shock absorber cylinders to the tank 72. However, the weight of theparts is still being imposed through the lift pistons 47 on the oil inthe head ends 50 of the lift cylinders 45 and in the lines 81, 82connected thereto, the pressure of this oil also being present in thehead ends 62 of the shock absorber cylinders to retain the pistons 63and rot lers 70 in their lowermost or extended position, the oil in thelines 81, 82 being at a relatively high pressure. The introduction offluid under pressure into the rod ends 51 of the lift cylinders and intothe rod ends 65 of the shock absorber cylinders will occur and willfirst contact the shock absorber rollers 70 with the pavement, the oilunder pressure in the head ends 62 of the cylinders 60 still being at ahigh value and preventing retraction of the shock absorber pistons 63upwardly in such cylinders until the rear wheels 14 are elevated fromthe pavement, the entire weight of the rear portion of the unit at firstbeing borne by the shock absorber rollers 70. However, the saw blades 32and depth-of-cut rollers 35 are still out of contact with the pavement.As an example, when the shock absorber wheels 14 first contact thepavement, the saw blades 32 may be located approximately 1% inches abovethe pavement R. Following contact of the wheels 70 with the pavement thefluid pressure in the rod ends 51,65 of the lift cylinders 45 and shockabsorber cylinders 60 increases due to flow of oil from the pump 71through the valve 74, such pressure increase also being imposed on thefluid in the rod ends of the shock absorber cylinders The fluid in thehead ends 62 of the shock absorber cylinders is then forced by theupward movement of the pistons 63 out through the choke orifices 84 andback through the valve 74 and the return line 75 to the tank 72, suchoutward flow permitting upward retraction of the pistons 63 and rods 64in the cylinders 60 and elevation of the shock rollers 70 to permit thegradual descent of the cutters 32 against and into the pavement to cutthe grooves S therewithin, as limited by engagement of the dcpth-of-cutrollers 35 with the pavement. The upward retraction of the shockabsorber rollers 72 and the descent of the cutters 32 and depth-of-cutrollers 35 occurs relatively slowly and at a uniform controlledvelocity, giving the cutters an opportunity to cut into the concretepavement to the desired depth, which, for example, may be one-sixteenthto one-eighteenth of an inch. The vehicle is then moved along thepavement by the power being transmitted from the engine 15 through thevehicle transmission to the front wheels 12, the rear wheels 14 merelyrotating freely since they are elevated from contact with the pavement.

in the event that descent of the movable frame 20, as a result ofintroducing fluid under pressure into the rod ends 51 of the liftcylinders 45, occurred rapidly, the cutters 32 would be prevented fromcontacting or impacting against the pavement, since the shock absorberrollers 70 will first contact the latter. Even if the movable frame 20were to drop for some reason, the shock absorber rollers 70 would firstcontact the pavement R and prevent the impacting of the cutters 32against the pavement. As a result of elevation of the grooving unit Gfrom the pavement, the fluid pressure automatically extends the shockabsorber pistons 63 and rods 64 and their associated wheels 70, wherebythey are in a position to initially reengage the pavement once more.

Iclaim:

1. ln a machine for performing a cutting action on a road way: a supportmovable generally vertically toward and from the roadway; cutter meanscarried by the support for cutting the roadway; means for moving saidsupport and cutter means towards and from the roadway; and shockabsorber means mounted on and carried by said support and movablyvertically with respect thereto and engageable with the roadway prior toengagement of said cutter means with the roadway, said shock absorbermeans embodying means for retarding descent of said support toward theroadway and of said cutter means into engagement with the roadway afterengagement of said shock absorber means with the roadway.

2. In a machine as defined in claim 1; and means responsive to operationof said moving means in elevating said support and cutter means forlowering said shock absorber means relative to said support and cuttermeans.

3. In a machine as defined in claim 1; and means responsive to operationof said moving means in lowering said support and cutter means forelevating said shock absorber means relative to said cutter means andsupport after engagement of said shock absorber means with the roadway.

4. in a machine as defined in claim 1; and instrumentalities responsiveto operation of said moving means in elevating said support and cuttermeans for lowering said shock absorber means relative to said supportand cutter means, said instrumentalities being responsive to operationof said moving means in lowering said support and cutter means forelevating said shock absorber means relative to said cutter means andsupport after an engagement of said shock absorber means with theroadway.

5. In a machine as defined in claim 1; said cutter means comprising agang of retractable parallel saw blades for cutting a plurality ofparallel grooves simultaneously in the roadway.

6. In a machine for performing a cutting action on a roadway: a supportmovable generally vertically toward and from the roadway; cutter meanscarried by said support for cutting the roadway; fluid operated meansfor moving said support and cutter means toward and from the roadway;fluid operated shock absorber means carried by said support andengageable with the roadway prior to engagement of said cutter meanswith the roadway for retarding descent of said cutter means intoengagement with the roadway.

7. In a machine as defined in claim 6; and means for directing fluidunder pressure simultaneously to said fluid operated means and fluidoperated shock absorber means for elevating said support and cuttermeans and for lowering said shock absorber means relative to said cuttermeans.

8. In a machine as defined in claim 6; and means for directing fluidunder pressure simultaneously to said fluid operated means fluidoperated shock absorber means for lowering said support and cutter meansand for elevating said shock absorber means relative to said cuttermeans after engagement of said shock absorber means with the roadway.

10. in a machine as defined in claim 6; and means for directing fluidunder pressure simultaneously to said fluid operated means and fluidoperated shock absorber means for elevating said support and cuttermeans and for lowering said shock absorber means relative to said cuttermeans; and means for directing fluid under pressure simultaneously tosaid fluid operated means and fluid operated shock absorber means forlowering said support and cutter means and for elevating said shockabsorber means relative to said cutter means after engagement of saidshock absorber means with the roadway.

10. In a machine as defined in claim 6; and means for directing fluidunder pressure simultaneously to said fluid operated means and fluidoperated shock absorber means for lowering said support and cutter meansand for elevating said shock absorber means relative to said cuttermeans after engagement of said shock absorber means with the roadway;and flow restricting means in said fluid directing means for retardingelevation of said shock absorber means shock absorber means with theroadway.

11. In a machine as defined in claim 6; said cutter means comprising agang of rotatable parallel saw blades for cutting a plurality ofparallel grooves simultaneously in the roadway.

12. In a machine for performing a cutting action on a roadway: a vehicleadapted to traverse the roadway and having a first frame; a second framemovable generally vertically toward and from the roadway cutter meanscarried by said second frame for cutting the roadway; first cylindermeans connected to one of said frames; first piston means slidable insaid cylinder means and connected to the other of said frames; fluidoperated shock absorber means carried by said second frame andcomprising a roadway contacting member second cylinder means; one ofsaid second cylinder means and second piston means being connected tosaid second frame, the other of said second cylinder means and secondpiston means being connected to said roadway contacting member; saidsecond cylinder means having fluid therein acting upon said secondcylinder means and second piston means whereby said roadway contactingmember engages the roadway prior to engagement of said cutter means withthe roadway for retarding descent of said cutter means into engagementwith the roadway.

13. in a machine as defined in claim 12; and means for directing fluidunder pressure to one portion of said first cylinder means and to oneportion of said second cylinder means for elevating said second frameand cutter means and for lowering said roadway contacting memberrelative to said cutter means.

14. In a machine as defined in claim 12; and means for directing fluidunder pressure simultaneously to one portion of said first cylindermeans and to one portion of said second cylinder means for lowering saidsecond frame and cutter means and for elevating said roadway contactingmember contacting relative to said cutter means after engagement of saidroadway contacting member with the roadway.

15. In a machine as defined in claim 12; and means for directing fluidunder pressure to one portion of said first cylinder means and to oneportion of said second cylinder means for elevating said second frameand cutter means and for elevating said second frame and cutter meansand for lowering said roadway contacting member relative to said cuttermeans; and means for directing fluid under pressure simultaneously toanother portion of said first cylinder means and to another portion ofsaid second cylinder means for lowering said frame and cutter means andfor elevating said roadway contacting member relative to said cuttermeans after engagement of said roadway contacting member with theroadway.

16. la a machine as defined in claim [2; and means for directing fluidunder pressure simultaneously to one portion of said first cylindermeans and to one portion of said second cylinder means for lowering saidsecond frame and cutter means and for elevating said roadway contactingmember relative to said cutter means after engagement of said roadwaycontacting member with the roadway; and flow restricting means in saidfluid directing means for retarding elevation of said roadway contactingmember relative to said cutter means after engagement of said roadwaycontacting member with the roadway.

17. In a machine as defined in claim 12, said cutter means comprising agang of rotatable parallel saw blades for cutting a plurality ofparallel grooves simultaneously in the roadway.

18. In a machine for cutting grooves in a set surface traversed byvehicles: a vehicle having a roadway engaging set of forward wheels anda roadway engaging set of rear wheels and including drive means for atleast one of said sets of wheels; a frame connected to said vehicle andmoving vertically with respect thereto; cutter means rotatably mountedon said frame; means for rotating said cutter means to cut grooves inthe roadway surface; means operatively connected between said vehicleand frame for moving said frame vertically to selectively elevate saidcutter means from the roadway surface or to shift said cutter means intoengagement with the roadway surface and elevate a set of wheels fromengagement with the roadway surface, whereby the weight of the frame anda portion of the weight of the vehicle are applied to said cutter means;said vehicle. frame and cutter means being moved along the roadwaysurface by said drive means rotating the set of wheels remaining inengagement with the roadway surface; and shock absorber means carried bysaid support and engageable with the roadway surface prior to engagementof said cutter means with the roadway surface for retarding descent ofsaid cutter means into engagement with the roadway surface.

19. In a machine as defined in claim 18; said means for moving saidframe comprising a first cylinder connected to said vehicle, a firstpiston slideable in said first cylinder and connected to said frame;said shock absorber means being mounted on said frame and including aroadway surface engaging member, a second cylinder connected to saidframe, and a second piston slidable in said second cylinder andconnected to said roadway surface engaging member; said second cylinderhaving fluid therein exerting pressure between said second cylinder andsecond piston to retard descent of said cutter means into engagementwith the roadway surface.

20. In a machine as defined in claim 18; said means for moving saidframe comprising a first cylinder connected to said vehicle, a firstpiston slidable in said first cylinder and connected to said frame; saidshock absorber means being mounted on said frame and including a roadwaysurface engaging member, a second cylinder connected to said frame, anda second piston slidable in said second cylinder and con nected to saidroadway surface engaging member; said second cylinder having fluidtherein exerting pressure between said second cylinder and second pistonto retard descent of said cutter means into engagement with the roadwaysurface; and means for directing fluid under pressure simultaneously toone portion of said first cylinder and to one portion of said secondcylinder for elevating said frame and cutter means and for lowering saidroadway surface engaging member relative to said cutter means.

21. In a machine as defined in claim 18; said means for moving saidframe comprising a first cylinder connected to said vehicle, a firstpiston slidable in said first cylinder and connected to said frame; saidshock absorber means being mounted on said frame and including a roadwaysurface engaging member, a second cylinder connected to said frame, anda second piston slidable in said second cylinder and connected to saidroadway surface engaging member; said second cylinder having fluidtherein exerting pressure between said second cylinder and second pistonto retard descent of said cutter means into engagement with the roadwaysurface; and means for directing fluid cylinder and to one portion ofsaid second cylinder for lowering said frame and cutter means and forelevating said roadway surface engaging member relative to said cuttermeans after engagement of said roadway surface engaging member with theroadway.

22. In a machine as defined in claim 18; said means for moving saidframe comprising a first cylinder connected to said vehicle, a firstpiston slidable in said first cylinder and connected to said frame; saidshock absorber means being mounted on said frame and including a roadwaysurface engaging member, a second cylinder connected to said frame, anda second piston slidable in said second cylinder and connected to saidroadway surface engaging member; said second cylinder having fluidtherein exerting pressure between said second cylinder and second pistonto retard descent of said cutter means into engagement with the roadwaysurface; and means for directing fluid under pressure simultaneously toone portion of said first cylinder and to one portion of said secondcylinder for elevating said frame and cutter means and for lowering saidroadway surface engaging member relative to said cutter means; and meansfor directing fiuid under pressure simultaneously to an other portion ofsaid first cylinder and to another portion of said second cylinder forlowering said frame and cutter means and for elevating said roadwaysurface engaging member relative to said cutter means after engagementof said roadway surface engaging member with the roadway surface.

23. In a machine ad defined in claim 18; said means for moving saidframe comprising a first cylinder connected to said vehicle, a firstpiston slidable in said first cylinder and connected to said frame; saidshock absorber means being mounted on said frame and including a roadwaysurface engaging member, a second cylinder connected to said frame, anda second piston slidable in said second cylinder and connected to saidroadway surface engaging member; said second cylinder having fluidtherein exerting pressure between said second cylinder and second pistonto retard descent of said cutter means into engagement with the roadwaysurface; and means for directing fluid under pressure simultaneously toone portion of said first cylinder and to one portion of said secondcylinder for elevating said frame and cutter means and for lowering saidroadway surface engaging member relative to said cutter means; and meansfor directing fluid under pres sure simultaneously to another portion ofsaid first cylinder and to another portion of said second cylinder forlowering said frame and cutter means and for elevating said roadwaysurface engaging member relative to said cutter means after engagementof said roadway surface engaging member with the roadway surface; andflow restricting means in said firstmentioned fluid directing means forretarding elevation of said roadway surface engaging member relative tosaid cutter means after engagement of said roadway surface engagingmember with the roadway surface.

24. In a machine as defined in claim 18; said means for moving saidframe comprising a first cylinder connected to said vehicle, a firstpiston slidable in said first cylinder and connected to said frame; saidshock absorber beans being mounted on said frame; said shock absorbermeans being mounted on said frame and including a roadway surfaceengaging member, a second cylinder connected to said frame, and s secondpiston slidable in said second cylinder and connected to said roadwaysurface engaging member; said second cylinder having fluid thereinexerting pressure between said second cylinder and second piston toretard descent of said cutter means into engagement with the roadwaysurface; and means for directing fluid under pressure simultaneously toone portion of said first cylinder and to one portion of said secondcylinder for elevating said frame and cutter means and for lowering saidroadway surface engaging member relative to said cutter means; and meansfor directing fluid under pressure simultaneously to another portion ofsaid first cylinder and to another portion of said second cylinder forlowering said frame and cutter means and for elevating said roadwaysurface engaging member relative to said cutter means after engagementof said roadway surface engaging member with the roadway surface; andflow restricting means in said firstmentioned fluid directing means forretarding elevation of said roadway surface engaging member relative tosaid cutter means after engagement of said roadway surface engagingmember with the roadway surface; said cutter means comprising a gang ofrotatable parallel saw blades for cutting a plurality of parallelgrooves simultaneously in the roadway surface.

UNITED STATES lA'lEN'i OFFICE CERTIFICATE OF CORREC'IION Patent No.r3,608,969 Dated September 28, 1971 1 v t JOSEPH s. FOWKES It iscertified that error appears in the above identificd parent and thatsaid Letters Patent are hereby corrected as shown below:

r Column- 6 line. 67 (claim 1, line 16) "movably" should be --movab1e--.

Column 7, line 20, cancel "retractable" and substitute --rotatabl-e--;line 39 (claim, 8, line 3), before "fluid" insert --and-- line 43-, thenumber of the claim designated "10" should be --9:'-; line 60 (claim 10,line 8) after "means" first occurrence) insert --relative to said cuttermeans a ter engagement of said; line 68 (claim 12, line 4) after"roadway insert a line 73 (claim 12, line 9), before "second" insert aColumn 8, line 1, after "means" (first occurrence) insert and secondpiston means slidable in said second cylinder, means--; lines 21 and 22(claim 14, lines 5 and 6), cancel "contacting"; lines 27 and 28 (claim15, lines 4 and 5) cancel "and for "elevating said second frame andcutter means"; line 51 (claim 18, line 1) "set" should be --roadway-.

Column 9, line 39 (claim 21, line 12) after "fluid" insert --underpressure simultaneously to one position of said first-;; line 60 (claim22, line 17) "an other" should be --anot er--. c

Column 10, lines 35 and 3b, cancel "said shock absorber beans beingmounted on said frame;"; line 39, "a" should be Signed and sealed this21st day of March 1972.

(SEAL) Attest z EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK AttestingOfficer Commissioner of Patents

1. In a machine for performing a cutting action on a roadway: a supportmovable generally vertically toward and from the roadway; cutter meanscarried by the support for cutting the roadway; means for moving saidsupport and cutter means towards and from the roadway; and shockabsorber means mounted on and carried by said support and movablevertically with respect thereto and engageable with the roadway prior toengagement of said cutter means with the roadway, said shock absorbermeans embodying means for retarding descent of said support toward theroadway and of said cutter means into engagement with the roadway afterengagement of said shock absorber means with the roadway.
 2. In amachine as defined in claim 1; and means responsive to operation of saidmoving means in elevating said support and cutter means for loweringsaid shock absorber means relative to said support and cutter means. 3.In a machine as defined in claim 1; and means responsive to operation ofsaid moving means in lowering said support and cutter means forelevating said shock absorber means relative to said cutter means andsupport after engagement of said shock absorber means with the roadway.4. In a machine as defined in claim 1; and instrumentalities responsiveto operation of said moving means in elevating said support and cuttermeans for lowering said shock absorber means relative to said supportand cutter means, said instrumentalities being responsive to operationof said moving means in lowering said support and cutter means forelevating said shock absorber means relative to said cutter means andsupport after engagemenT of said shock absorber means with the roadway.5. In a machine as defined in claim 1; said cutter means comprising agang of rotatable parallel saw blades for cutting a plurality ofparallel grooves simultaneously in the roadway.
 6. In a machine forperforming a cutting action on a roadway: a support movable generallyvertically toward and from the roadway; cutter means carried by saidsupport for cutting the roadway; fluid operated means for moving saidsupport and cutter means toward and from the roadway; fluid operatedshock absorber means carried by said support and engageable with theroadway prior to engagement of said cutter means with the roadway forretarding descent of said cutter means into engagement with the roadway.7. In a machine as defined in claim 6; and means for directing fluidunder pressure simultaneously to said fluid operated means and fluidoperated shock absorber means for elevating said support and cuttermeans and for lowering said shock absorber means relative to said cuttermeans.
 8. In a machine as defined in claim 6; and means for directingfluid under pressure simultaneously to said fluid operated means fluidoperated shock absorber means for lowering said support and cutter meansand for elevating said shock absorber means relative to said cuttermeans after engagement of said shock absorber means with the roadway. 9.In a machine as defined in claim 6; and means for directing fluid underpressure simultaneously to said fluid operated means and fluid operatedshock absorber means for elevating said support and cutter means and forlowering said shock absorber means relative to said cutter means; andmeans for directing fluid under pressure simultaneously to said fluidoperated means and fluid operated shock absorber means for lowering saidsupport and cutter means and for elevating said shock absorber meansrelative to said cutter means after engagement of said shock absorbermeans with the roadway.
 10. In a machine as defined in claim 6; andmeans for directing fluid under pressure simultaneously to said fluidoperated means and fluid operated shock absorber means for lowering saidsupport and cutter means and for elevating said shock absorber meansrelative to said cutter means after engagement of said shock absorbermeans with the roadway; and flow restricting means in said fluiddirecting means for retarding elevation of said shock absorber meansrelative to said cutter means after engagement of said shock absorbermeans with the roadway.
 11. In a machine as defined in claim 6; saidcutter means comprising a gang of rotatable parallel saw blades forcutting a plurality of parallel grooves simultaneously in the roadway.12. In a machine for performing a cutting action on a roadway: a vehicleadapted to traverse the roadway and having a first frame; a second framemovable generally vertically toward and from the roadway; cutter meanscarried by said second frame for cutting the roadway; first cylindermeans connected to one of said frames; first piston means slidable insaid cylinder means and connected to the other of said frames; fluidoperated shock absorber means carried by said second frame andcomprising a roadway contacting member, second cylinder means, andsecond piston means slidable in said second cylinder means; one of saidsecond cylinder means and second piston means being connected to saidsecond frame, the other of said second cylinder means and second pistonmeans being connected to said roadway contacting member; said secondcylinder means having fluid therein acting upon said second cylindermeans and second piston means whereby said roadway contacting memberengages the roadway prior to engagement of said cutter means with theroadway for retarding descent of said cutter means into engagement withthe roadway.
 13. In a machine as defined in claim 12; and means fordirecting fluid under pressure to one portion of said first cylindermeans and to one portion of said second cylinder meanS for elevatingsaid second frame and cutter means and for lowering said roadwaycontacting member relative to said cutter means.
 14. In a machine asdefined in claim 12; and means for directing fluid under pressuresimultaneously to one portion of said first cylinder means and to oneportion of said second cylinder means for lowering said second frame andcutter means and for elevating said roadway contacting member contactingrelative to said cutter means after engagement of said roadwaycontacting member with the roadway.
 15. In a machine as defined in claim12; and means for directing fluid under pressure to one portion of saidfirst cylinder means and to one portion of said second cylinder meansfor elevating said second frame and cutter means and for lowering saidroadway contacting member relative to said cutter means; and means fordirecting fluid under pressure simultaneously to another portion of saidfirst cylinder means and to another portion of said second cylindermeans for lowering said frame and cutter means and for elevating saidroadway contacting member relative to said cutter means after engagementof said roadway contacting member with the roadway.
 16. In a machine asdefined in claim 12; and means for directing fluid under pressuresimultaneously to one portion of said first cylinder means and to oneportion of said second cylinder means for lowering said second frame andcutter means and for elevating said roadway contacting member relativeto said cutter means after engagement of said roadway contacting memberwith the roadway; and flow restricting means in said fluid directingmeans for retarding elevation of said roadway contacting member relativeto said cutter means after engagement of said roadway contacting memberwith the roadway.
 17. In a machine as defined in claim 12, said cuttermeans comprising a gang of rotatable parallel saw blades for cutting aplurality of parallel grooves simultaneously in the roadway.
 18. In amachine for cutting grooves in a roadway surface traversed by vehicles:a vehicle having a roadway engaging set of forward wheels and a roadwayengaging set of rear wheels and including drive means for at least oneof said sets of wheels; a frame connected to said vehicle and movingvertically with respect thereto; cutter means rotatably mounted on saidframe; means for rotating said cutter means to cut grooves in theroadway surface; means operatively connected between said vehicle andframe for moving said frame vertically to selectively elevate saidcutter means from the roadway surface or to shift said cutter means intoengagement with the roadway surface and elevate a set of wheels fromengagement with the roadway surface, whereby the weight of the frame anda portion of the weight of the vehicle are applied to said cutter means;said vehicle, frame and cutter means being moved along the roadwaysurface by said drive means rotating the set of wheels remaining inengagement with the roadway surface; and shock absorber means carried bysaid support and engageable with the roadway surface prior to engagementof said cutter means with the roadway surface for retarding descent ofsaid cutter means into engagement with the roadway surface.
 19. In amachine as defined in claim 18; said means for moving said framecomprising a first cylinder connected to said vehicle, a first pistonslideable in said first cylinder and connected to said frame; said shockabsorber means being mounted on said frame and including a roadwaysurface engaging member, a second cylinder connected to said frame, anda second piston slidable in said second cylinder and connected to saidroadway surface engaging member; said second cylinder having fluidtherein exerting pressure between said second cylinder and second pistonto retard descent of said cutter means into engagement with the roadwaysurface.
 20. In a machine as defined in claim 18; said means for movingsaid frame comprising a first cylinder connected to said vehicle, afirst piston slidable in said first cylinder and connected to saidframe; said shock absorber means being mounted on said frame andincluding a roadway surface engaging member, a second cylinder connectedto said frame, and a second piston slidable in said second cylinder andconnected to said roadway surface engaging member; said second cylinderhaving fluid therein exerting pressure between said second cylinder andsecond piston to retard descent of said cutter means into engagementwith the roadway surface; and means for directing fluid under pressuresimultaneously to one portion of said first cylinder and to one portionof said second cylinder for elevating said frame and cutter means andfor lowering said roadway surface engaging member relative to saidcutter means.
 21. In a machine as defined in claim 18; said means formoving said frame comprising a first cylinder connected to said vehicle,a first piston slidable in said first cylinder and connected to saidframe; said shock absorber means being mounted on said frame andincluding a roadway surface engaging member, a second cylinder connectedto said frame, and a second piston slidable in said second cylinder andconnected to said roadway surface engaging member; said second cylinderhaving fluid therein exerting pressure between said second cylinder andsecond piston to retard descent of said cutter means into engagementwith the roadway surface; and means for directing fluid under pressuresimultaneously to one portion of said first cylinder and to one portionof said second cylinder for lowering said frame and cutter means and forelevating said roadway surface engaging member relative to said cuttermeans after engagement of said roadway surface engaging member with theroadway.
 22. In a machine as defined in claim 18; said means for movingsaid frame comprising a first cylinder connected to said vehicle, afirst piston slidable in said first cylinder and connected to saidframe; said shock absorber means being mounted on said frame andincluding a roadway surface engaging member, a second cylinder connectedto said frame, and a second piston slidable in said second cylinder andconnected to said roadway surface engaging member; said second cylinderhaving fluid therein exerting pressure between said second cylinder andsecond piston to retard descent of said cutter means into engagementwith the roadway surface; and means for directing fluid under pressuresimultaneously to one portion of said first cylinder and to one portionof said second cylinder for elevating said frame and cutter means andfor lowering said roadway surface engaging member relative to saidcutter means; and means for directing fluid under pressuresimultaneously to another portion of said first cylinder and to anotherportion of said second cylinder for lowering said frame and cutter meansand for elevating said roadway surface engaging member relative to saidcutter means after engagement of said roadway surface engaging memberwith the roadway surface.
 23. In a machine as defined in claim 18; saidmeans for moving said frame comprising a first cylinder connected tosaid vehicle, a first piston slidable in said first cylinder andconnected to said frame; said shock absorber means being mounted on saidframe and including a roadway surface engaging member, a second cylinderconnected to said frame, and a second piston slidable in said secondcylinder and connected to said roadway surface engaging member; saidsecond cylinder having fluid therein exerting pressure between saidsecond cylinder and second piston to retard descent of said cutter meansinto engagement with the roadway surface; and means for directing fluidunder pressure simultaneously to one portion of said first cylinder andto one portion of said second cylinder for elevating said frame andcutter means and for lowering said roadway surface engaging memberrelative to said cutter means; and means for directing fluid underpressure simultaneously to another portiOn of said first cylinder and toanother portion of said second cylinder for lowering said frame andcutter means and for elevating said roadway surface engaging memberrelative to said cutter means after engagement of said roadway surfaceengaging member with the roadway surface; and flow restricting means insaid first-mentioned fluid directing means for retarding elevation ofsaid roadway surface engaging member relative to said cutter means afterengagement of said roadway surface engaging member with the roadwaysurface.
 24. In a machine as defined in claim 18; said means for movingsaid frame comprising a first cylinder connected to said vehicle, afirst piston slidable in said first cylinder and connected to saidframe; said shock absorber means being mounted on said frame andincluding a roadway surface engaging member, a second cylinder connectedto said frame, and a second piston slidable in said second cylinder andconnected to said roadway surface engaging member; said second cylinderhaving fluid therein exerting pressure between said second cylinder andsecond piston to retard descent of said cutter means into engagementwith the roadway surface; and means for directing fluid under pressuresimultaneously to one portion of said first cylinder and to one portionof said second cylinder for elevating said frame and cutter means andfor lowering said roadway surface engaging member relative to saidcutter means; and means for directing fluid under pressuresimultaneously to another portion of said first cylinder and to anotherportion of said second cylinder for lowering said frame and cutter meansand for elevating said roadway surface engaging member with the roadwaysurface; and flow restricting means in said first-mentioned fluiddirecting means for retarding elevation of said roadway surface engagingmember relative to said cutter means after engagement of said roadwaysurface engaging member with the roadway surface; said cutter meanscomprising a gang of rotatable parallel saw blades for cutting aplurality of parallel grooves simultaneously in the roadway surface.